Methods and devices for dual-channel monitoring of safety-relevant sensor signals can be used, for example, in monitoring the pressure of what is referred to as a torque-vectoring-system, i.e., for monitoring the hydraulic pressure acting on a friction clutch of the torque-vectoring-system. For example, the hydraulic pressure needed for actuating the two friction clutches via which the drive torque is transmitted to one of the two half-shafts of the drive axle, may not exceed a certain threshold value. If excessively high pressure is detected, then the torque-vectoring-system must be deactivated for safety reasons.
In principle, the method and devices initially specified could be used particularly in all areas in which safety-critical applications in accordance with SIL 3-Standard (Safety Integrity Level 3-Standard) are realized. Such applications are generally those that can pose danger to life and limb for humans. In addition to the specified torque-vectoring-system, additional applications in the field of passenger cars are conceivable, such as in the area of steering or braking systems, where appropriate safety-critical parameters must be monitored.
In accordance with the SIL 3-Standard, pressure monitoring in torque-vectoring-systems must for example be redundant, i.e. designed as dual channel. In monitoring systems of the prior art the pressure values to be monitored are thus processed in a completely dual-channel manner on the basis of hardware, i.e. measured separately from one another, converted into the appropriate electrical signals, checked for permissible/impermissible values and a warning/control signal is generated if one of the monitored signals is found to be at an impermissible level. This means that in systems of the prior art, both the sensors for measuring the parameters being monitored, the input-side transmission channels, the evaluation units usually designed as microprocessors and the output-side transmission channels connected thereto must each be present twice as hardware.
Redundantly furnishing evaluation units in particular constitutes a significant cost factor for this type of safety systems. Because, however, experts continue to definitively argue that two separate evaluation units are indispensable for analyzing the sensor signals being monitored, the option of allowing for cost-savings while simultaneously meeting the required safety conditions is not seen as a possibility.